The Raven class ships are small long range research vessels which the Federation ordered for non-starfleet programs. Since they are not Starfleet vessels they do not need to have any military capability, while diplomatic capability is very limited. The ships can accommodate several dozen people in reasonable comfort for several months at a time, but the flight and engine systems are highly automated and even one or two people can operate these ships indefinitely.
The Raven class can carry various modular sensor packages, allowing them to be refitted as needed for individual missions. As a result they have been a popular choice for scientists in various fields. One notable mission was that undertaken by the Hansen family, who used a Raven class vessel in their ill-fated attempt to prove the existence of the Borg. Their ship disappeared in 2355 and their mission was considered a failure - indeed many took this failure as a sign that the rumoured cybernetic civilization was indeed mythical, as had been previously thought. Not until 2374 did the crew of the USS Voyager discover that the Hansens had in fact succeeded in finding the Borg, only to be assimilated by them. The Raven apparently crash-landed in Bomar space during the Borg attack, undergoing catastrophic damage in the process. It remained here until it remained until discovered by Voyager.5

• D342 USS Raven NAR-32450